hotplug.c 2.2 KB

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  1. /*
  2. * linux/arch/arm/mach-realview/hotplug.c
  3. *
  4. * Copyright (C) 2002 ARM Ltd.
  5. * All Rights Reserved
  6. *
  7. * This program is free software; you can redistribute it and/or modify
  8. * it under the terms of the GNU General Public License version 2 as
  9. * published by the Free Software Foundation.
  10. */
  11. #include <linux/kernel.h>
  12. #include <linux/errno.h>
  13. #include <linux/smp.h>
  14. #include <asm/smp_plat.h>
  15. #include <asm/cp15.h>
  16. static inline void cpu_enter_lowpower(void)
  17. {
  18. unsigned int v;
  19. asm volatile(
  20. "mcr p15, 0, %1, c7, c5, 0\n"
  21. " mcr p15, 0, %1, c7, c10, 4\n"
  22. /*
  23. * Turn off coherency
  24. */
  25. " mrc p15, 0, %0, c1, c0, 1\n"
  26. " bic %0, %0, %3\n"
  27. " mcr p15, 0, %0, c1, c0, 1\n"
  28. " mrc p15, 0, %0, c1, c0, 0\n"
  29. " bic %0, %0, %2\n"
  30. " mcr p15, 0, %0, c1, c0, 0\n"
  31. : "=&r" (v)
  32. : "r" (0), "Ir" (CR_C), "Ir" (0x40)
  33. : "cc");
  34. }
  35. static inline void cpu_leave_lowpower(void)
  36. {
  37. unsigned int v;
  38. asm volatile(
  39. "mrc p15, 0, %0, c1, c0, 0\n"
  40. " orr %0, %0, %1\n"
  41. " mcr p15, 0, %0, c1, c0, 0\n"
  42. " mrc p15, 0, %0, c1, c0, 1\n"
  43. " orr %0, %0, %2\n"
  44. " mcr p15, 0, %0, c1, c0, 1\n"
  45. : "=&r" (v)
  46. : "Ir" (CR_C), "Ir" (0x40)
  47. : "cc");
  48. }
  49. static inline void platform_do_lowpower(unsigned int cpu, int *spurious)
  50. {
  51. /*
  52. * there is no power-control hardware on this platform, so all
  53. * we can do is put the core into WFI; this is safe as the calling
  54. * code will have already disabled interrupts
  55. */
  56. for (;;) {
  57. wfi();
  58. if (pen_release == cpu_logical_map(cpu)) {
  59. /*
  60. * OK, proper wakeup, we're done
  61. */
  62. break;
  63. }
  64. /*
  65. * Getting here, means that we have come out of WFI without
  66. * having been woken up - this shouldn't happen
  67. *
  68. * Just note it happening - when we're woken, we can report
  69. * its occurrence.
  70. */
  71. (*spurious)++;
  72. }
  73. }
  74. /*
  75. * platform-specific code to shutdown a CPU
  76. *
  77. * Called with IRQs disabled
  78. */
  79. void __ref vexpress_cpu_die(unsigned int cpu)
  80. {
  81. int spurious = 0;
  82. /*
  83. * we're ready for shutdown now, so do it
  84. */
  85. cpu_enter_lowpower();
  86. platform_do_lowpower(cpu, &spurious);
  87. /*
  88. * bring this CPU back into the world of cache
  89. * coherency, and then restore interrupts
  90. */
  91. cpu_leave_lowpower();
  92. if (spurious)
  93. pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
  94. }